#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <vector>
#include <cmath>
#include <queue>
#include <deque>
#include <set>

#define flr(x,l,r) for (int x = l; x <= r; ++ x)
#define frl(x,r,l) for (int x = r; x >= l; -- x)
#define fmp(x,t) for (int x = h[t]; ~x; x = ne[x])
#define LL long long 
#define mt memset
#define my memcpy 
#define szf sizeof
#define INF 0x3f3f3f3f
#define in(x) scanf("%d", &x)
#define out(x) printf("%d", x)
#define inll(x) scanf("%lld", &x)
#define outll(x) printf("%lld", x)
#define pn printf("\n")
#define con continue
#define bk break
#define vc vector
#define pb push_back
#define sz size
#define PII pair<int, int>
#define x first
#define y second
#define P_q priority_queue
#define ft front
#define pf push_front
#define popf pop_front
#define it insert
#define ct count

using namespace std;

const int N = 5010;

int s[N][N];

int main() {
    int n, R;
    in(n), in(R);
    
    while (n -- ) {
        int x, y, w;
        in(x), in(y), in(w);
        x ++ , y ++ ;
        s[x][y] += w;
    }
    
    flr (i, 1, 5001)
        flr (j, 1, 5001)
            s[i][j] += s[i - 1][j] + s[i][j - 1] - s[i - 1][j - 1];
            
    int res = 0;
    R = min(R, 5001);
    flr (i, R, 5001)
        flr (j, R, 5001)
            res = max(res, s[i][j] - s[i - R][j] - s[i][j - R] + s[i - R][j - R]);
    
    out(res), pn;
    
    return 0;
}